Analogous to time signals that can be composed of multiple frequency functions, we use uniquely structured orthogonal spatial modes to create different beam shapes. We tailor the spatial structure by judiciously choosing a weighted combination of multiple modal states within an orthogonal orbital angular momentum (OAM) basis set, creating desired beam intensity "shapes." The weights of the OAM ...

The following study deals with the updating the finite element model of structures using the operational modal analysis. The updating process uses an evolutionary optimization algorithm, namely bees algorithm which applies instinctive behavior of honeybees for finding food sources. To determine the uncertain updated parameters such as geometry and material properties of the structure, local and...

The use of equivalent beam models to estimate the dynamical characteristics complex tall buildings has been investigated by several authors. main reason is structural response estimation stochastic loads, such as wind and earthquake, using a reduced number degrees freedom, which reduces computational costs therefore gives designer an effective tool explore possible solutions. In this paper, nov...

In this study, a novel and very simple finite element procedure is presented for free vibration and buckling analysis of slim beam-like structures damaged by edge cracks. A cracked region of a beam is modeled using a very short element with reduced second moment of area (I). For computing reduced I in a cracked region, the elementary theory of bending of beams and local flexibility approach are...

Abstract: Modal analysis is a powerful technique for understanding the behavior and performance of structures. Modal analysis can be conducted via artificial excitation, e.g. shaker or instrument hammer excitation. Input force and output responses are measured. That is normally referred to as experimental modal analysis (EMA). EMA consists of three steps: data acquisition, system identificatio...

In this paper, we design a modal controller for conservative ßexible systems that uses distributed sensing. A spatial Þlter design based on the eigenfunctions coupled with a velocity observer prevents spillover instabilities in the closed-loop system. The proposed control is proven to stabilize a discrete set of controlled modes without destabilizing the remaining, residual modes. We then apply...

The long-term goal of this research is to develop optimal array signal processing techniques for passive source localization in littoral shallow-water environments. It has long been known that multi-modal dispersion in a shallow water waveguide degrades the performance of bearing estimates by conventional plane-wave beamforming. This is due to spurious effects unique to the waveguide environmen...

We describe an approach to determining both the angular and the radial modal content of a scalar optical beam in terms of optical angular momentum modes. A modified Mach-Zehnder interferometer that incorporates a spatial rotator to determine the angular modes and an optical realization of the fractional Hankel transform (fHT) to determine the radial modes is analyzed. Varying the rotation angle...

In order to relieve traffic congestion, irregularly-shaped bridges have been widely used in urban overpasses. However, the analysis on modal characteristics of irregularly-shaped bridges is not exhaustive, and the effect of design parameters on modal characteristics will be deeply investigated in future studies. In this paper, a novel strategy based on a free-interface mode synthesis algorithm ...